This section provides background information related to the present disclosure which is not necessarily prior art.
Products such as automobiles, boats, military and industrial equipment that are transported by land, sea or air, are susceptible to damage from their environment. During transportation, such products are either placed inside shipping containers or they are carried open to the environment. In the case of industrial and especially military vehicles and equipment, which are subject to long periods of outdoor storage, where the environment can cause severe corrosion damage; a protective cover becomes an essential product. Methods of protecting such objects have been developed over the years and, U.S. Pat. Nos. 5,491,017; 5,523,812; 5,712,008; 6,562,740B1, and 5,736,231 each of which is hereby expressly incorporated by reference, all provide an extensive background on protecting articles during transportation and/or storage over long periods of time. However, the products described under each of these patents do not sufficiently address problems which arise from moisture and/or condensation.
Either during transportation or in storage, items to be protected are often subject to condensation. In nature condensation occurs when a vapor is cooled to its dew point. Water vapor condenses onto a surface when the surface of that object is cooler then the temperature of the water vapor. Condensation occurs regularly in the environment especially during early hours of the day, when the weather temperature raises faster then the surface temperatures of vehicles and other objects, especially objects made from metal.
Infrastructure, such as highway bridges, with open metal beams, railroad and airport equipment, as well as utilities such as open pipelines and cell phone towers and their components are all subject to repeat condensation as change, in temperature occur.
According to Corrosion Basics: An Introduction by Pierre R. Roberge; a fundamental requirement for atmospheric-corrosion processes is the presence of a thin film electrolyte that can form on metallic surfaces when exposed to a critical level of humidity. The critical level of humidity is material dependent, but most objects are subject to higher levels of corrosion in higher relative humidity environments (coastal areas) however, when relative humidity is below 30%, the corrosion is less likely to occur. Condensation that occurs on the surface of a metal object, a vehicle or a boat represents 100% Relative Humidity. From the time the condensation starts on a surface to the time when temperatures reach to equilibrium, the relative humidity on that object is 100%, therefore increasing the rate of corrosion and possibly growth of mold and mildew on that surface.
Pollutants that are present in the environment where condensation occurs also play a role. For example, sulfur dioxide and nitrogen oxides, which are the gaseous product of the combustion of fuels that contain sulfur such as coal, diesel fuel, gasoline, and natural gas also contribute greatly to the extent of corrosion. If these pollutants are already present on the surface of the object before being wrapped, when condensation takes place they help increase the rate of corrosion under the wrapping material.
Micro-perforation of films has been used in an effort to address moisture/condensation issues, but such applications decrease the physical properties of the film. In case of a shrink film, micro-perforations get larger due to heat applied and make the film even weaker. In order to protect an object/surface from environmental hazards, including corrosion, it is important that the object being wrapped is also dry on the inside. In order to create and more importantly keep a dry environment, it is preferred that the wrapping material start removing moisture/condensed water from the surface being protected, as quickly as possible and not let it back in which often occurs when micro-perforated films are employed. Under all anti-condensating applications it is preferred that the wrapping material not allow any liquid water, such as rain, inside. It is also preferred that the amount of water vapor going away from the surface be greater then the amount of water vapor going towards the surface.